Haftar, who was exiled in the United States for two decades, returned to Libya in 2011 when the revolution erupted, commanding forces that eventually toppled dictator Muammar Gaddafi.

On Saturday, the Tripoli-based Interior Minister of the Presidential Council's government Fathi Bashagha accused the United Arab Emirates (UAE) of reportedly sending Haftar military support in "clear violation of the global law".

The presidency released photos showing Haftar, dressed in a blue suit, sitting with Sisi and his head of intelligence Abbas Kamel.

But Fayez al-Serraj's National Accord government has managed to halt the advance for now, aided by forces with machine-guns on pickups and steel containers across the road into Tripoli.

Bashagha told a United States-based Arabic language TV channel on Friday that they received information about an aircraft that came from UAE and landed in Benghazi's Benina Airport with military equipment for Haftar's forces in violation of the UN arms embargo. Islamist militants have since controlled large parts of the vast country, including the capital Tripoli.

Gen Haftar frames his march on Tripoli as part of his fight against Islamic militants and to restore law and order in Libya, goals that are, at least in theory, in line with the policies on Libya embraced by Egypt and Gen Haftar's west European allies.

The WHO said in a tweet that 561 others had been wounded since commander Khalifa Haftar launched an offensive earlier this month to take Tripoli, which is now controlled by a UN-backed government.

More than 13,500 people had been displaced by the clashes, including 4,000 in the past 24 hours, and more than 900 residents are living in shelters, the U.N. Office for the Coordination of Humanitarian Affairs said Saturday.

"The humanitarian community is concerned about rising numbers of civilian casualties, including medical personnel", OCHA Libya said.

"Our position will not change", United Nations envoy Ghassan Salame tweeted. Both sides have carried our airstrikes in the town, and a spokesman for the Libyan National Army said it has stepped up airstrikes on its rivals in the past two days.

"The humanitarian community repeats its warning that continuing to attack medical and civilian facilities is a violation of global humanitarian law and human rights law", OCHA said in a statement.